BUSI 721Jones Graduate School of BusinessRice UniversityKerry Back
\[x_s + \sum_{i=1}^n w_i = 1\]
\[ (1-w)r_s + w \bar{r} = r_s + (\bar{r}-r_s)x_s\]
\[w \bar{r} - (w-1)r_b = r_b + (\bar{r}-r_b)w\]